Method and apparatus for placer mining



April 9, 1935. e. A. MACREADY METHOD AND APPARATUS FOR PLACER MININGFiled 001;. 11, 1933 3 Sheets-Sheet 1 April 9, 1935. G. A. MACREADY 7METHOD AND APPARATUS FOR PLACER MINING 5 Sheets-Sheet 2 Filed Oct. 11,1933 April 9, 1935. a. A. MACREADY METHOD AND APPARATUS FOR PLACERMINING 3 Sheets-Sheet 3 Filed Obt. 11, 1953 Patented Apr. 9, 1935'"METHOD ANDIAP PARATUS FOR P I JACERj "x M :17 i v .1.

a Ge e -c i re a Losl-Angeles, cam,

- Application Octoberll, 19:33,"Serial No, 693;2l0f i, p 9:Cl aims.&.(o1. 262+2 fl= it My invention relates to a method and apl a ratus formining shallow ores in open excavae tions, extracting thevaluableportion therefrom, f and disposing of the tailings or rejected portionk;My invention is particularly adapted to the 'working of 'low gradeplacergold depositsffor 7 ing and merly worked byhydraulic 'mining, to the'dry;

placer goldgravels'of arid regions, totin' and platinum gravelscand toother deposits in which the volu'rne of tailings greatly exceeds thevolume? of values extracted.

Ar -object ofmy invention a method-of min;- f

treating ore .orgravel in such a way 1 v tailingsarejeconomicallydisposedof" by depositing them in a 'pile or heap and using thedeposited tailings as a foundation for, a

that

treating plantover which said plant maybe advanced bodily as the tailingpile is extendedtq follow the working face of the ore or gravel,

I An object: of my invention is "amethod of dis? posing of tailingswithout the expensejo f transporting-them to a dump after treatment;, Toaccomplish this I dischargethe tailingsfdirectly from 'a treatment plantonto the flank of a tail ing pile to extend the pile and advance theplant,

' bodily over the surface of the pileto; follow the extension of thepile, using the tailing pile as. the ioundation for supporting theplant.

"Objectsof my invention are a method and an apparatus for economicallyplacer ore, extracting values therefrom, and disposing of the tailings.

An object of my invention-is an apparatus for;

open out or placer mining consisting of adrag line excavator and abodily movable unit ii'i'- eluding a platform carrying a mast from-whichthe excavator is operated and a' separatorftof extract values from oreand rejecttailings over" the side of the platform.

'An object of my invention is'a methodand 7 large proportion .of

againj V r An-object of my invention is a method and'ap-- paratus fortreating clayey gold gravelsf by screening the fine clay particles fromthesand and treating each separately-to recover goldi It is well knownthat clay has a habitat picking up i gold from sluices and interferingwith good' re-V In the treatment of gold placer gravel the pro-: portionof valuable product (gold).v is extremely small in comparison to therejected worthless ma--" 5 terial (tailings) For example, gravel containn for gold it isnecessary 'the injunction.

' apparatus by which'valuable mineral is'w ashed; vfrom a gravel ore bywater treatment; and a the water salvaged for use dredge usuallyprohibits dredgingfl r l a v Throughout the mining'districts ofCaliiornia,

ten cents gold cubic yard contains only one part oif'golfd to about"100,000,000 parts offwor'th-V less material (by volume)'conditum,.introduces'ca factor into mining'placer gold that isf oftenoverlooked with disastrous results: namely,-

theeconomical disposal of enormous quantities] a of worthless tailings;

'I'he n ost important problem peculiartothe' mining of low gradegoldjplacergravel's is: eco t riomical disposal of a large (:11iarititiesgofivs rorthlessm tailings, a,

This "problem does not trouble gravel mining v for road or structuralmaterial becausethe ma trial 'mined' is a marketable product p disposed"of; by salesa Neither does, it ,.tri: uble the undergroundininerbecause; only higher grade rocx p can be profitably minedi u'ndergroundand fpthe proportiomof-A tailings tovalues is less' ffl But.init;hemining Iofelowi grade placer fgravels rjtofhandl'e and diS'pOSeof j anextremely large yardage "or worthless {tailing material ata lowic'ost in,order toshowaprofit; For xam m yqram e ri iniiigfcouldpdig orie verycheaply j'largeduantities'; couldfextract thev gold cheaply; :but wasunable jtofsurvivebecause 25 of inabilityato dispose of tailings whenenjoined by. courtslinr 1884 against dllj ipirig t aili ngsi into 7navigable. riverslf Hydraulic mining, which had t been a: flourishing,.industry in California before 1884. practically ceased a. 'few' ears;after;

Gold dredging, ii Y vhaa'agigr a ts be n; successful largely because the,disposal of tailings' was solved by'stacking them in the 'rearofgthe-lin wh h ;r 1s f ats+ l e in eilones nomi w mm;a r ds b ing-te dredgefloats onwater near the top of the tail;,--- l ingpileandthe stacker isnot ;called on to lift an excessive height. In arid regionsther'difiiculty in maintaining a pond in which to float 2.

Arizona and 'other regions" there still remain errori l mous'deposits'of lowj-"grade gold placer gravel unsuitable for dredgingi or hydraulicmining 5t; which await the deve1oprnent-pff=aneconomical V e 'method formining and treating: This par ticularly true of large grav eldepositsfformerly hv a pked in, th "(Sierra N vada, mounta andiofdeposits in dry desert regions where corif ditions are notlsu'itable formaintaining a dredge pond; or; wherelhydraulic minin isl prohibited.

' Ap 'm QP QK JP QVidG$ a et i n apparatus' suitable foreconomicalhandling 55 1.

receptacle l2 up toward sheave I 6 until it'asisomer its load is hauledalong trackcable l by cable' 2 I operated from the'thir'ddrum 9' of-thesame hoist. 'The hoist 5'is illustrated 'ontop of gravel bank G near itsedge and consists of three; cable drums or reels 5, I and 9 driventhrough clutches;

by motor I Q. The clutches and brakes of each drumcan be operated bycontrol leverssuch as n 1 Levelinguis aidedby having conveyors M and42'.

at Ill r The form of dumping bucket D illustrated in Figure 1 consistsof a receptacle I2 hung by pivoti Hi froma carrier frame l3 which inturn is mounted'on roller sheaves or---wheels l5 to roll along trackcable I-. (A third sheave wheel I6 is mounted on the carrier l3 andcable '2' passes thereover. When'bucket D is hoisted clear of the groundby tightening cable l'to position I and ishauled along track cablel'the-load receptacle I 2 takes a position illustratedat D in which thebucket is suspended from pivot H1-with-therear end 'hangingbelowthe-mouth: The end of cable I ismadefast to sheave l'l atthe rap er mast3 and cable 2 passes through sheave I'I; -When over sheaves l6 and II todraw the rearend of sumes a position as atD" with therear end elevatedto dump the load.'-' When the load "has been dumped the bucket is hauledback-along track cable I by reelingin cable 4 and c'able' l'is slackenedto lower the bucketto the gravelbank' for another load. i a

Treatment plant P is-mounte'd on abodily movf able floor or frameconsisting of skids l8 on which may be cross timbers IQ for stiffnessand the floor planking 20. The floor is supported on the top ofthetailing fpileasa foundation and can be moved bodily'by skiddingoronrollersso that it is kept close enough to the advancing edge of thetailing pile in order that the tailingsmay be discharged Onto the slopeor fiank'of the tail-' ing pile.

The form of mast or boom 3 consists of two upright posts 36 having a capcross piece 31' sup-1} porting sheave l1. The mast is held steadyibyguylines 38' and diagonal Ore dumped frombucket D falls on a grizzly 2 Iwhich allows the moderate size particles of ore to fall through intohopper 22 and rejects the oversize bouldersdown chute to the bc'ttomo'ffthe tailing pile] Oreor gravel in hop'per' 22-pass'es: throughgate doors and screw feeders'23 so that a moderately uniform rate (offeed is" deliveredto a revolving screen or tromfnel 24. "Screening pileto become a. partbf the tailing pile.

Fines and water passing through trommel perforations go to-gold1savingS1uices"25. "The sluices are of types common to dredges and placerminingin general and consist of inclined'sluices having riiiles on theirfloors for'trapping gold or other heavymineral product. The sluices arecleaned up periodically to obtain the values.

The sluic'esl discharge onto dewatering sc 'reer 1s 26 which allow waterand fine mud to- 'dr'op' through into vats 21 and 29 and passthe gritand sand oversize onto conveyor belts 4i and 42.

7 motor: :32 Io'r' by braces 39 so that it is fast to the floor. l r

method isillustrated by The conveyor transportthe sand out over theslope of the tailing pile and drop it into sub ni1es"43 and H to formthe upper'portionof' the main tailing-pile T.- The top surface of thepile:

can be kept level byoccassional strokes of -a hand shovelso that thefinished tailin'g dumpwillhave a'smooth surface of -'the'finematerial.

projeetjunequal distances. r a v i The'heaviest portion of the mudsettlesto the bottom of vats: 2T and 29 r from which it can bedischarged i continuously or atintervals through valves or outlets '45.Partially cleared water overflows into central vat 28, where additionalmud :settles and is drawn off through outletl lii; l The clearest 'waterin' the topof vat 28 isdrawn pumped into the sluices for use' inj theprocess again. Additional" clear water must of course be suppliedto'make-up' for that-drawn ofifrom the bottoms of the vats and for waterclinging to'the 'tailingsx Themud'andiwat'er drawn'oif; fromsettlingivats: can: be into; settling ponds or .7

feederand conveyor can be suppliedby shafts and belting from a singlegasoline or electric individual electric motors wherever required;

1Grizz1y- 2l and chute 33'are supported on a 34 and1conveyors4| and 42are suspendedz'from piece. Iv

I-loist 5 and lant .P can be anchored against or dead men; Later'alshifting is doneby wrapping a'rope52- around acathadfl and pulling ona'cable suchas 5 L f V I I {There is considerable-option in-thedirection at cross piece on braces'39 anda cross piecej48-rest-" ing onangle braces-4 9. The outer ends of "chute shifting by cables'50and 5|attached tostiunpsii -which operations can? be carried. The plant P land tailing pile-can be moved directly toward hoist5 to'jcutand fill a-narrow trench'. 'If-the' deposit is wideit is to zig zag across a widecut as illustrated. in Figure 2 whereprevious posi tions of plant? andhoist 5'we're at? and. 5; If

the'deposits are high benches along a gulch or valley thev tailingpilecan be deposited as a strip parallel: to the gulch and the drag lineoperatedat right angles to the pile to bring down-ma: terial from thehi111sideS;'-" For mining uneven or sloping ground the treatment plantcan be provided with sills of unequal or. tapered thickness' so that-thefloor and vats can bemaintained level one. tailing pile having '3 asloping-uppersurface; It is therefore evident I r that ,applicants-method adaptable to areas I which are too rough for a floatingdredge. If A modified form 'of apparatus embodying the same principles forcarrying out-applicant's Figures 536 andi; de

scribed as-follows:

'-'I'he digging element D jconsistsf bf a bucket} i 0 I such a's 'thelconventional Page or Sauermann types" operated by" two cable's- IUZ andH13 from-drums lfli and'illl respectively oni 'shaft I; The drums aredriven byianbleetricmotor" ll 0% and; are controlled" brakes and'clutchesif operatedby levers at l-ll where the operatorhas Vaclear'*1v"iew"offthe eitc'avatiofifsluices and? screens. The bucketIfll-gathers a' load of gravel when dragged against rbank. G bycableylfl;

I Cable IE3 is next reeledin hoisting'the bucket IIH to the topof mast.I I3, cable I02 bein'g kept'tight; while paying? outbybrake or clutch soas to suspend the bucket above the-ground. CablefjIflZ? isslackedoff:completely when the bucket. reaches the top of the mastwhich;in-turn-slacksdump:

. cable IM to drop the forward 'endof bucket wl,

and discharge itsload. 1

The load is dumped...onto. s hee t I I.5 and grizzly. 'I I6. ,Jets ofwater. suppliedtbygan electrically.

" driven centrifugal pumpz I I]; through nozzle I I8;

' sprays on the gravelto dishitegratei itgand. wash:

the fines through thegrizzlyiI-J S: and the oversize to chuteIZadownWhichbouldersfaretdischargeda 'to tailin'g pile T..;..Fi nes.-drop: throughv to finer;

mesh screens, 1212,1122; I-ZSLWhich; separate the materialinto;gradedjgsizes,1, each to :be. treated I separately iorrecoveryofgold gorrother valuables:

' The number of screens and coarseness of each:

grade should {be selected. to. suit, thetgravel 'orl Sore of-each:individuallnfline. scheme 51s "as; follows:

-A. typical gradingiz The first grizzly I I5 discharges i larger. than Q1 inch pieces toi'tailings; 5 The second, screen I2I:;-

discharges 1- to 3-inch material tea-nu et trap or jig 124 Where largenuggets maynbecaptured; Third screen IiZ discharges th to 11-inch ma-;.

terial. to launder; I-and ,thence to one set of sluices I 21. Fourthscreen.v I23dischargesl/fiflth'.

to th inch. material to launder 126' andpthence,

; to another. grQup of sluicesj I28; Fines Lsmallen; than l/fiilthinchpassing through screen I 23 dropi onto an amalgamated plate .129 andthenceover ,Water supplied byelectricall ydriven centriiuj-g alzp mpH9I.to.laun ders 'I.25...a.ndi; I26 washes;

. the material into distributors I85 and I0] which 1 feedsluices throughindividual;doors or outlets similar to thestandard practicejofyfloating'gold.

' dredges. ,Sluices} J 21 andjaj 2.81 are equipped with-J ter toidropthroughfrinto;vatsv I33. andiglfl and the conventional-rifles;commonlyused on;float.

ing dredges .for recovery ofgpld. and. discharge to: dewatering screens;I3 I and IBZ :whi'ch..allow ;wa-..-

discharge thesandandiggravelonto conveyors" The pulp I and 136whichextend-zoverthe' slope of -theg tailing pile {anddischargertheflsolids ontothe p leT- passing through screen I23 (thelast grading screenL dropsgonto amalgamated plate ,l-za here .the lineancinour. gold reacts with; the

amalgam and sticks. OverfioWing 'pulp passes. over a short section, of-riffles or;an1algam:.traps- I30 to prevent loss of goldoramalgam whichmay? accidentally have dislodgedg; from iplate. I29 *and; dischargesinto :vatliijl; -;Grit ahd, ,heavy;mu'd;

settle in vat; I3-I::al dfare 1dischargedlperiodi cally; or continuouslyby a QSLICtl'OIl DHmIJ' -LOI'J- bodily across the topof tailing pile.8I6;on which through valve .I38 ;;;.Iluid :from the-top of-yat I3!overflows into"vat I39 where additional mud settles and, may bewithdrawntln1'0uglr outlet) M t r by su on umn. Nat-I39 overflows-mare ly clear',.watelpinto .sma vat I 40; which is the; suctionvat for pump; Igl. lGlear water' from. a;

' t s p y shqu yil era sl lte rat; .4 t mw,

. pe q w t .)wit ii awr ;w. he udlost clinging. toz oyersize. so ,tthatvwater can be 75.

cont uous pnlied..-to-thesr z.z1y by; p mp-l The m d a rofith o shou -2an may; berun to waste or: if; in a'desert, region iverted ta s t gpndst salvagewater.

, In order to give maximum capacitythe screens} H I I, me d zlm 'b -s ned b t v rups from framepiece; I59 so that th y maybe ivenasshakingniotion, Pitmen I43 and. M4:

driven by electric motor I45 are provided for shaking the screens andalso-jig or nugget trap J24. Conveyorsshown are operated by electricmotors as self contained units and the-dewater ing screens may also be'provided-with'rnotorsto ive vibration forincreased capacity. Auxiliarypump; I 53 nay. also; be provided together" with a length oi flexiblej.hpscalfqr miscellaneous. use ineluding pumpingheavymud from vats, I

Electric motors ;,are illustrated; with this form but where electric.power is. not, available. steam or. internal combustionmotors canbeused, -I: A. cross piece .146 supported by angle braces I41 and framepiece .159 provided a sfupportout over the slope ,of-ithe; tailing pi efrom which the outer ends, ofi chutes 'and conveyors may be suspended ider i' xtend their ha e-w t.

heads 8 and Mq on the ends of drum;shaft I provide means for exertingpull on ropes for miscellaneous purposes, 7 The. entire plant includingthe drag line excavator is 'mounted on a plat:- form or: floorI55provided rwith skids I56 (or wheels or rollersl as a bodily movableunit sup p t n th t ..the::ta i e sot at it can be moved bodilyacrossthe surface thereof,

Force 'for moving is applied by ordinary lifting jacks I51 bracedagainst-posts or deadmen I58.

It is. readily seen that the tai i s dischargedfrom the plant ontotheside slope or fiank of the tailing.- pile' buildup or extend the pile.about as fast as'mining proceeds lwhenever the dischargeI r m c ute r cov yo ds e q e. th

desiredlevelgof the tailing pile a. few strokes oi ahand shovel or smalldrag scraper pulled by mast but exceptin 5 roperf'rom the cat head serveto level the top of discharge onto the flank of the pile, r v F ure ihows1as m e ap ra s or applying .applicants method to' ore of adifferent type ii -which thevaluesare-chunksjor pieces which.

can. be separated by hand and visual observation atable 888Anpperator-BQS by means oi -a hoe '8 I0 or other tooldrags the valuablepieces ofi the 'platformonto pile 8 II fir other convenient place andpushes the 1 valueless I tailing material oh the end of the platform todrop on the flank of;

tailing pilel8 l2'r,Platform 8.01 ispushed orpulled the pile. The entireplant is advanced bodily, either continuously. or. at intervalsby:pulling w th a cable or by pushing with jacks .I5'I. so I that. asfastas the tailing pile is ex-l tended the discharge is 'keptclose-enough; 'to the edgeof E the tailing :pile for tailings to 'it issupportedsoas to follow thepxtension' of the growing pile and dischargetailings onto the flank of the pile. The method of extracting the;valuable portion of ore inthis case ishandsort;

ing andithesepaliator is a platform and hoe.

ype h c ithe a s are ov rsi e a erial, suchas phosphate nodulesorgcon'cretions of valuable Ina'Ite Tia -ina loose matrix.'Itcon'si'stsof against a bank of placer ore to loadsaid recep-.

a drag line excavator 9M operated by cables 902 and 993 from: inastBMI:cables 'a'r'e op'erated by 'drum's r9595 driven by motor SGGI- MaSt i904iscarrieddn a platform-crisper 901:. Thexcavator dumps its load 'on'screen or grizaly 9fl8; Fines drop through thebhute BBQ-which in turndischarges them as" tail-lugs to tailing pile; 9 l0. Oversize materialrolls dovm'the screer'fto"chute 9.1! from which it is taken'b'y handordiv'er'ted to sacks as at EH2. Chute-909and scrcn-908 are supported oncross "pieces-.9 Iii-{and 9 l 4 onfthelegs of mast 9M andon-{support1$l5.= The entire fioortfi'i, with screer'i, mast and'clrurns, ispu'shed or pulled bodilyas a. unit'across thetop offtailingpile fild upon which itis supported so as'to follow the, extension ofthegrowing tailing-"pile and discharge t'ailings onto the fia'iikiof the''pile. In this case the separatoI is a simple-screenand Numerous othermodifications;accessories and details of construction an'd'oa'erations'can bedescribed but will be omitted because'it isbelievedthat sufiicint, description has" already been given to teach applicantsinvention to others.

In resume of the foregoing pages it is seen that an'imp'ortant advancehas been made in the art of placer mining by applicants noveland.economical method and apparatus fordisposal and use of tailings, brieflydescribed as follows and in the appended claims. 7 V

Ore is dug from open cuts by a drag line excavator, transported directlytothe top of a mast, and delivered to a separator (such assluices orscreens) at the foot of the mast wherein valuable portions are extractedfrom the ore and tailings discharged directly onto the flank of atailing pile. The mast and separator are carried on a platform or flooras a bodily movable unit or treatment plant. The plant is supported onthe top of the tailing pile near the edge so that tailings dischargedirect from the plant onto the flank of the pile extending the pile; Asfast as the detailmay be made without departing from the spirit or scopeof the invention as defined'in the appended claims.

I claim as my invention: 1. A method of mining. and treating placer orewhich consists of dragging'a digging receptacle tacle with ore,transporting said receptacle with its load bodily to a mast carried byatreatment plant supported on the top of a pile of tailings frompreviously treated ore, dumping said load from. an elevation near thetop of said mast into said plant, returning said receptacle to the bankrepeatedly for additional loads of ore; extracting valuable portionsfromsaid ore in said plant, discharging the rejected tailings over the sideof said plant onto the flank of said tailing pile to extend said pile,and moving said plant bodily as a single unit across the top surface ofsaid tailing pile to follow the extension of said pile closely enoughfor all tailings to discharge onto the flank of said pile.

2. An apparatus for placer mining consisting the, side ao f-rsaidplatform; l

including'i a :iplatfor'm' 'gcarrying" thereongla i'mast fromwhich saidexcavato'risioperatediand 'aiiseparator'adapted :to extract values: fromore deliv-; ere'dby isaid excavator and rejecttailing's over 1;;

3. An apparatus for min ing and treating placer ore consisting of adragline excavatorpperated by cables and a bodily movable foundationiioor supporting thereon a mast 5 from which said ex- 'cavator is.operated to" dig ore from a placer de-.-f

posit and deliver 'said'ore to a separatorsupported on said flooradjacent said mast, and a separator, adapted to extract thevaluable-portions from'said ore and discharge theitailings rejected overthe.

V 4; An apparatus "for mining and treating placer oreconsistinglof adragline excavator operated cavator'is operated to digore fromaplace depositand discharge tailing's rejected over thesideof by cables and abodilymovable foundation floor supporting the'r'e'on a mast frorniwhichsaid ex'-,

and deliver 'said ore' to a screen" adjacent said. mast; a'fscreefiadjacent 'said-imast adaptedkto 1 separate and'f' 'discharge oversizematerialjgffrdm said ore' overthef side-of said 11001, a separator.adapted to receivenndersizefinaterial from said screen,' extract thevaluableportions therefrom said floor-adjacent the discharged oversize,;and

motive power for operating said separator.

5. An apparatus for mining and treating placer ore consisting of a dragline excavator operated i by cables and a bodily movable foundationfloor supporting thereon a mast from which said excavator is operatedtodig ore from a placer deposit i and deliver said ore to a screenadjacent said mast, a screen adjacent said mast adapted .to separate anddischarge oversize material from said ore over the side' of said .floor,a separator adapted to receive undersize material from said screen andextract valuable portions therefrom,

a'pump connected to supply water to wash material through saidseparator, dewatering means adapted to salvage water discharged fromsaid separator and discharge solids separated therefrom over the side ofsaid floor adjacent the discharged oversize, and motive power foroperating said pump, separator and dewatering means. 6. An apparatus formining and treating placer V ore consisting of a drag line excavatoroperated by cables and a bodily movable foundation floor supportingthereon a mast from which said exca- 7 vator isop'erated to dig ore froma placer deposit and deliver said ore to a screen adjacent said mast, ascreen adjacentsaid mast adapted to separate anddischargeoversize'material from said oreover the side of said floor, a separatoradapted to receive undersize material from-said screen and extractvaluable portions therefrom, 1

dewatering means adapted to salvage'water discharged from said separatorand discharge solidsseparated therefrom over the side of said flooradjacent the discharged oversize, vats receiving said salvaged waterprovided with outlets for discharging mud settlings from the water, apump connected to pump water from said vat to said separator, and motivepower for operating said pump-separator and dewatering means.

7. A method of mining andtreating placer ore which consists of diggingand transporting ore froma placer deposit to a treatment/plant supportedon top of a pile of tailings from previously treated ore, extracting thevaluable portions from said ore, discharging the tailings rejected bysaid "the flank of said pile V w 8. .A method of'mining and a l i which;consists of dragging a--digging receptacle against abankof placer ore toload'said recepgtacle with oreptransporting said receptacle with itsload bodilyto a mast carried by a treatment plant directly onto theflanks of said a ing we; the iar'ge pieces being depositedznear thebottom of; the; pile andthe small pieces :near othe top of v -whichconsists of dragging a digging receptacle 7 against a depositofplacerore toloadsaid receptaclewith ore, raising said r'eceptacle clearof the ground surface, transportingsaid receptacle with thegpile, andmoving said plantbodily across. the

.top of said pile to follow the extension of'said J pile'clos'elyenough'for tailings to discharge onto treating. placerore plantsupported one pile oftailings from previously treated ore, dumping saidload from an gelev ation adjacent the top of said mast into said plant,returning said receptacle to the bank repeatedly for additional loads 7of. are, screening the ore in said plant, discharging theioversize overthe edge of said plant fonto the-flankcf said tailing pile; treatingthe,undersize in, said plant tov extract valuable products therefrom,discharg-' ring the tailings ircm the treated undersize over theedge ofsaidplant adjacent theL-oyersize discharge directly onto the flank 0fSaidtailing pile, and inojving said treatz nent plant; bodily as .asinglevunit across, the top suriace'of said'tailing pile to follow theextension of 'said pile closely 19953711 r V a "enough for all-tailingstodischa-rge directly from "the treatment plant onto the flankof saidpile.

g 9.1. A method of mining and treating placer ore itsload bodily andabove the ground surface directly from saiddeposit to a. mast carried'bya treatment plant supported on a'pile' of tailings ifrom'previouslytreated ore, dumping said load into said plant from an elevationadjacent the top of said mast whilefsupporting weight of said receptacleby said mast, returning said receptacle to said deposit repeatedly foradditional loads of ore, sizing the delivered'ore into portions in saidplant fextracting valuable products-in said plant from one ofthesizedportions, discharging anings'of spent ore over the side of said plantdirectly onto the flank of the tailing pile, and movingsaidtreatmentplant bodily as a single unit across-the uppersurface ofsaid tailing pile to follow the extension of said pile closely enoughfor all tailings to discharge directly from said plant onto the'flank ofsaid pile.

" GEORGE A. MACREADY.

